N-Boryl-Substituted Bis(amino)stannylenes and -plumbylenes

Ever since their first synthesis in 1974 monomeric tin(II) and lead(II) amides have attracted con­ siderable interest as a consequence of their carbenoid electronic structure [1 6]. Although the sub­ stituents at the nitrogen atoms have been varied to some extent, N-dialkylboryl groups have received only scant attention. One attempt to use a N-dimethylboryl group has afforded a dimer after elim ­ ination o f trimethylborane [7]. Recently we have found a convenient access to N-lithio-N-trimethylsilyl-9-amino-9-borabicyclo[3.3.1]nonane (1) [8], Similar to alkali metal bis(trimethylsilyl)amides [9], this reagent 1 proves useful in the synthesis o f monomeric low co-ordinated metal amides. In the following we describe the synthesis and characteri­ zation of the tin(II) amide 2, of the lead(II) amide 3, and of the trimethyland dimethyltin amides 4 and 5 for comparison.